Photosensitized transparent element



3,002,851 PHGTGSENSITIZED TRANSPARENT ELEMENT Jack L. Sui-kin, ClevelandHeights, and Ronald C. Vickery, Novelty, Ghio, assignors to HorizonsIncorporated, Princeton, Ni, a corporation of-New Jersey r No Drawing.Filed Mar. 28, 1957, Ser. No. 649,009 2 Claims. (Cl. 117-34) Thisinvention relates to a sensitized transparent member of rigid plastic.More particularly, it relates to articles such as a card for datarecording systems or an identification card, or even a slide forsubsequent projection, or other articles formed of a presensitizedtransparent rigid thermoplastic member.

Data recording systems based on cards are becoming increasingly usefulin the complex society of the present day. Business machines have beendevised for retrieving the information stored and recorded on cards,either in the form of perforations or in the form of visible symbols.Recent data recording systems even involve cards which combine aperforated portion with a film secured to a window cut out of the cardproper. Such cards are tedious to manufacture and are subject to failurewhen the film separates from the supporting card portion.

To overcome some of the disadvantages inherent in such cards, it hasbeen proposed that transparent cards may be fabricated from syntheticthermoplastic materials and sensitized either by direct imposition onthe surface of the plastic of a means which will be photosensitive asfor example is shown in Patent 2,781,265, issued February 12, 1957, orby the incorporation of a photosensitive system within the basematerial.

In the first of these approaches it has been observed that thesuperimposed photosensitive material tends to curl, or otherwise causedestruction of the base material. Furthermore, the scratch resistance ofthe photosensitive material is particularly low. In order to reduce thesus ceptibility to destruction, it has been proposed to reinforce thebase material by means of an additional supporting layer but this hasbeen found to seriously diminish the transparency of the over-alllaminated product.

The second approach, in which a photosensitive material is incorporatedwithin the plastic system, usually requires expensive materials andcareful control of the processing conditions in order to avoidundesirable side reactions.

We have now found a third method for incorporating the photosensitivematerial into the plastic or resinous material constituting theinformation card which is free from the disadvantages attendant oneither of the previously practiced methods.

In accordance with our invention, a suitable synthetic plastic material,such as polyvinyl chloride, polyvinyl acetate, polystyrene, or the like,is formed into a flat card of the desired size and shape. Where theoriginal material is not initially translucent, it is converted to atranslucent blank by any suitable treatment as will later be described.Thereafter, the translucent blank is coated with a photosensitivecomposition such as one incorporating diazo photosensitive materials. Inorder to cause the photosensitive material to become firmly embeddedwithin the plastic matrix, we have found it to be necessary to heat thecomposite to a temperature not exceeding about 130 C. while applying amoderate pressure to the composite. Under these conditions thephotosensitive material migrates into the plastic base to a suflicientextent to obtain the desired benefits and to avoid the disadvantagesfound in prior art devices. The photosensitivity of the diazo materialis not destroyed provided the temperature is not increased unduly andprovided further that the duration of the heating step ted States PatentPatented @ct. 3, 1961 is suitably restricted. The resulting sensitizedmember has, by this treatment, been converted from a translucentmaterial to a transparent material. After photoexposing, it may bedeveloped in the usual way, for example, by 5 exposure to ammonia vaporsor by the application of a wet alkaline solution of a suitable coupler.The following examples will serve to further illustrate our invention.

Example I Sheets of polyvinyl chloride were coated with Diazo N3CF (pdiazo-diphenylamine formaldehyde condensate-2ZnCl The resulting coatedarticle was heated in an oven at 120 C. while subjected to a pressuresufficient to cause flow (640 p.s.i.). At five-minute intervals sheetswere withdrawn from the oven and tested for photosensitivity. It wasfound that even after twenty minutes at 120 C. the photosensitivity ofthe heat-treated sensitized plastic was not impaired to any noticeable2O extent.

Example I] Example 111 Examples I and II were repeated using polystyrenesheets which had been rendered translucent by etching the polystyrenechemically with tetrahydrofuran in water. Other etching media, and evenmechanical means such as sandblasting may be provided to render thethermoplastic translucent.

Example IV The experiment of Example I was repeated with Diazo N26(p-diazo-N-ethyl-N-beta hydroxyethylaniline- /2ZnCl with similarresults.

By means of the heat and pressure applied to the base material after thecoating of diazo has been applied, the base is converted from atranslucent material to a transparent material and hence meets therequirements for modern data storage cards in this respect. It will beseen, therefore, that the heating operation by means of which thesensitized material is caused to be impregnated into the plastic base,accomplishes two purposes; not only does it render the resulting blanktransparent, it also serves to distribute the sensitized material Withinthe body of the blank and thereby avoid the tendency to curl experiencedwith prior art coated plastic base materials.

While We have disclosed specific diazonium compounds in connection withthe described examples, it will be understood that by varying thecouplers, many colors over a considerable range of the spectrum may beobtained.

The use of a roughened and translucent substrate is preferred because itcontributes to the tendency of the diazo material to adhere to the base,but we wish it understood that material which is initially smooth andtransparent may be processed in accordance with our invention.

Having now disclosed our invention in accordance with the patentstatutes, we claim:

1. A method of forming a transparent photosensitized element of rigidvinyl plastic material selected from the group consisting of polyvinylacetate, polyvinyl chloride and polystyrene which comprises: applying asolution of a photosensitive diazo coating to a solid transparent baseReferences Cited in the file of this patent composed of said vinylplastic and thereafter concurrent- 1y subjecting the coated base to atemperature between UNHED STATES PATENTS about 100 C. and 150 C., and apressure of at least 1,966,412 Krieger July 10, 1934 500. p.s.i for atime sufiicient to permit the diazo coat- 5 2,501,874 Peterson Mall 1950ing material to migrate into the body of the base material 2,593,9 8Slifkin Apr. 22, 1952 but not sufiicient to destroy the photosensitivityof said 2,598,453 Slifkin May 27, 1952 diazo coating material, 2,602,740Van Der Grinten July 8, 1952 2. The method of claim 1 wherein thepressure is be- 2,602,742 Buskes et a1. July 8, 1952 tween 500 psi. and1000 psi. 10 2,613,149 Unkauf Oct. 7, 1952

1. A METHOD OF FORMING A TRANSPARENT PHOTOSENSITIZED ELEMENT OF RIGIDVINYL PLASTIC MATERIAL SELECTED FROM THE GROUP CONSISTING OF POLYVINYLACETATE, POLYVINYL CHLORIDE AND POLYSTYRENE WHICH COMPRISES: APPLYING ASOLUTION OF A PHOTOSENSITIVE DIAZO COATING TO A SOLID TRANSPARENT BASECOMPOSED OF SAID VINYL PLASTIC AND THEREAFTER CONCURRENTLY SUBJECTINGTHE COATED BASE TO A TEMPERATURE BETWEEN ABOUT 100*C. AND 150*C., AND APRESSURE OF AT LEAST 500 P.S.I., FOR A TIME SUFFICIENT TO PERMIT THEDIAZO COATING MATERIAL TO MIGRATE INTO THE BODY OF THE BASE MATERIAL BUTNOT SUFFICIENT TO DESTROY THE PHOTOSENSITIVITY OF SAID DIAZO COATINGMATERIAL.